The alteration of the colour of keratinous fibres, in particular human hair, by the application of hair dyes is well known. In order to provide the consumer with the hair colour and the intensity of colour desired, a very complex chemical process is utilized. Non permanent hair colourant formulations typically comprise a non permanent dye such as direct dyes and or pigments which are deposited on to the surface of the hair and are gradually washed out over successive washing cycles. Permanent hair colourant formulations typically comprise oxidative hair dye precursors, which can diffuse into the hair through the cuticle and into the cortex where they can then react with each other and suitable oxidising agents to form the end dye molecules. Due to the large size of these resultant molecules they are unable to readily diffuse out of the hair during subsequent washing with water and/or detergents; hence delivering the consumer-desired permanency of colour. The reaction typically takes place in an aggressive environment at approximately pH 8 to 11 in the presence of an alkalizing agent and in the presence of an oxidizing agent. Moreover, the consumer repeats this process regularly in order to maintain the desired hair colour shade and the intensity of colour and to ensure continual, even coverage of the hair including coverage of new hair growth. Hair bleaching and highlighting compositions further typically utilize a strong oxidizing agent such as hydrogen peroxide and a persulphate salt in order to lighten the hair colour.
However, despite the fact that commercial hair colourant products have been available for many years, the products still exhibit a number of consumer-related deficiencies. The initial colour result, obtained immediately after colouring the hair, changes over time during the subsequent days and weeks resulting in both a change in colour intensity and shine, and colour tonality of the hair. Whilst not wishing to be bound to theory, this change in colour is thought to be exaggerated when the hair is in poor condition. Hair which has been permanently coloured typically has a poor condition, which manifests itself in the presence of a hydrophilic surface and chemical damage to hair proteins caused by the chemical process of colouring, and poorer cuticle integrity. This poor condition increases during the interval between hair colouring events. Further to the impact of enhancing the change of colour and shine during the time period in between colouring events, the poor condition of the hair leads to an increased difficulty of detangling, combing and styling the hair.
Many attempts have been made to improve the colour and damage profile of hair colourants. These have typically resided in the development of new dye precursors, and combinations of dye precursors to enhance the so called “washfade” profile. Despite offering some advantages, this approach does not provide sufficient advantages in colour maintenance overtime, and is not effective for all desired shades. Alternatively, the use of oxidative dyes in combination with pre-formed direct dyes within a single composition or as separate application steps has been taught. Such products may yield more intense initial colour, but without however the long term desired colour profile and with unacceptable variations in root to tip colour uptake and hair condition.
Durable silicone conditioner treatment compositions have been described in the following publications: EP1356802, EP1356803, EP1358865, EP1357143, EP1356801, EP1356800 and EP1358864 to improve the condition of hair over the time period in between colouring events. However the problem of colour maintenance is not addressed.
Attempts have also been made to “seal” in the delivered colour by improving the hair condition. Whilst, this provides some limited improvement of colour maintenance over time, it is not sufficient to mitigate all of the current deficiencies observed by the consumer. Thus, in summary, none of the above currently described solutions to improve the colour maintenance over the time period in between colouring events are entirely satisfactory and there thus still exists a need to improve the colour maintenance in-between colouring events.
It has now been surprisingly found that application routines whereby a specific durable silicone conditioner treatment composition is applied to the hair after oxidative colouration, prior to at least one subsequent application of a colour refresher, overcomes at least one of these drawbacks. In particular, the present invention delivers the required initial colour and shine which is furthermore maintained over a longer time period without the need for an additional oxidative colouring event.
Whilst not wishing to be bound by theory, it is believed that the application of durable silicone conditioner treatment enhances the colour fade profile by one or more mechanisms. Firstly, by enhancing the condition of the hair, less mechanical damage occurs to the individual fibers, thereby enhancing their integrity. This in turn slows down the diffusion process of dyes from within the hair, which will lead to the maintenance of the oxidative colour for a longer time period. Secondly, the durable silicone conditioner treatment is also believed to alter the surface properties of coloured hair, thereby restoring some level of hydrophobicity to the hair surface. Consequently the rate at which water can diffuse into the hair and remove the oxidative dyes is also reduced. Moreover, the subsequent application of a colour refresher in the period of days and weeks after the oxidative colouring event enables the preformed dyes within the colour refresher to be taken onto the hair, further compensating for any loss in colour intensity or tone. In addition the restoration of the hydrophobicity of the hair along the entire hair shaft from root to tip allows for the more even uptake of the colour refresher preformed dyes. Furthermore due to the presence of the silicone conditioner treatment on the surface of the hair shaft which improves the cuticle condition, the wash fastness profile of the colour refresher preformed dyes is also improved. Finally the repeated application of the durable silicone conditioner with the colour refresher preformed dyes will further enhance these benefits.